Forged Half Coupling Manufacturer, Supplier & Exporter
A forged half coupling has a socket weld or threaded connection at one end only; the other end is welded directly onto a pipe, header or vessel to create a small branch outlet. Raaj Fittings manufactures and exports half couplings to ASME B16.11, from ⅛" to 4" NPS, in stainless steel, duplex, nickel alloys, carbon steel and alloy steel.
Half couplings are a quick and economical way to add a small connection — for a thermowell, pressure gauge, vent, drain or sample point — to a larger line or vessel. A hole is cut in the run pipe, the half coupling is set on or into it and welded, and the free end accepts the branch pipe or instrument.
All half couplings are supplied with EN 10204 3.1 mill test certificates, with 3.2 certification and third-party inspection on request.
We export forged half couplings to EPC contractors, plant operators and stockists across the Middle East and GCC, Europe and the Americas — with NPT threads for US and Gulf projects or BSP threads where European and Middle Eastern specifications call for them.
Half Coupling Specifications
⅛" NPS to 4" NPS (DN 6 to DN 100)
Socket weld: Class 3000, 6000 and 9000. Threaded: Class 2000, 3000 and 6000
Socket weld or female threaded (NPT / BSPT / BSPP)
Plain end, square-cut or bevelled to order for set-on or set-in welding
Forged or machined from forged bar, then CNC machined
EN 10204 3.1 mill test certificate as standard; EN 10204 3.2 on request
Materials & Grades
We supply forged half couplings in the following materials and grades. All grades are supplied with EN 10204 3.1 / 3.2 Mill Test Certificates.
Stainless Steel Forged Half Couplings
Stainless steel forged fittings deliver excellent corrosion resistance in chemical, pharmaceutical, food processing, and marine environments. All grades supplied to ASTM A182 specification.
(ASTM A182 F304 / F304L) General corrosion resistance; food processing, dairy, and chemical service
(ASTM A182 F316 / F316L) Superior chloride and acid resistance; pharmaceutical, offshore, and chemical processing
(ASTM A182 F316H) Elevated-temperature creep strength for high-temperature process service
(ASTM A182 F317 / F317L) Higher molybdenum content; superior corrosion resistance in concentrated acid service
(ASTM A182 F321) Titanium-stabilised; resists sensitisation at sustained elevated temperatures
(ASTM A182 F347) Columbium-stabilised; used in heat exchangers and high-temperature piping
Duplex & Super Duplex Stainless Steel Forged Half Couplings
Delivering approximately twice the yield strength of austenitic stainless steel with excellent resistance to stress corrosion cracking, pitting, and erosion — ideal for offshore, subsea, and chemical processing environments.
(UNS S31803 / S32205, ASTM A182 F51) Offshore topsides, chemical plant, and seawater cooling systems
(UNS S32750, ASTM A182 F53) Subsea equipment, desalination, and high-chloride offshore service
(UNS S32760, ASTM A182 F55) High-temperature, high-chloride offshore and subsea service applications
Nickel Alloy Forged Half Couplings
For the most severe corrosive, high-temperature, and sour service environments where standard stainless steel grades are insufficient.
(UNS N06600) High-temperature oxidation and carburisation resistance
(UNS N06625) Outstanding corrosion resistance; offshore, chemical, and subsea service
(UNS N08825) Resistance to phosphoric and sulfuric acids; FGD and chemical plant
(UNS N10276) Universal corrosion resistance across the widest range of aggressive media
(UNS N06022) Superior resistance to oxidising and reducing acids and pitting attack
(UNS N04400) Seawater, hydrofluoric acid, and marine and alkali service
(UNS N08020) Engineered for sulfuric acid and aggressive chemical process service
Exceptional corrosion resistance in seawater and oxidising media at low density
Carbon Steel Forged Half Couplings
Carbon steel is the standard material for forged fittings in general-purpose, hydrocarbon, steam, and elevated-temperature service. The primary grade for forged carbon steel fittings is ASTM A105.
Primary grade for forged carbon steel fittings and flanges — covers ambient and elevated-temperature service in pressurised piping systems.
Low-temperature carbon steel, impact-tested for service down to -46°C (-50°F) — LNG, cold climate, and cryogenic piping applications.
Low-temperature carbon steel, impact-tested to -101°C (-150°F) — for the most demanding cold-temperature service applications.
Alloy Steel Forged Half Couplings
Chromium-molybdenum alloy steel grades for high-temperature, high-pressure service in power generation, petrochemical, and refinery applications. All grades supplied to ASTM A182 specification.
(5% Cr · ½% Mo) Refinery hydroprocessing and high-temperature service
(9% Cr · 1% Mo) High-temperature steam and hydrogen-rich process service
(1¼% Cr · ½% Mo) Thermal power plant steam, feedwater, and reheat piping
(2¼% Cr · 1% Mo) Reactors and high-temperature pressure piping in petrochemical plants
(9% Cr · 1% Mo · V · Nb) Ultra-supercritical power plant main steam and hot reheat piping
How Half Couplings Are Used
The half coupling is essentially half of a full coupling. Its plain end is welded to the outside of the run pipe or vessel shell (set-on), or inserted into the hole and welded (set-in), using a full-penetration or fillet weld as required by the piping or pressure vessel code. The socket or thread at the free end then takes the branch.
- Instrument connections — thermowells, pressure gauges and transmitters.
- Vents and drains — small outlets at high and low points of lines and vessels.
- Sample points — compact take-offs for sampling and analysers.
- Tank and vessel nozzles — small threaded connections on storage tanks and equipment.
Reinforcement
Cutting a hole in a pipe weakens it, and the piping code may require the branch to be reinforced. For small branches on thick pipes the half coupling’s own wall may be sufficient; where it is not, an integrally reinforced branch outlet to MSS SP-97 is often specified instead. Your piping engineer will confirm which is required.
Closing a Half Coupling
Spare or test connections made with half couplings are closed with a threaded forged plug or a socket weld forged cap. Select the half coupling class to suit the branch pipe schedule, as with other ASME B16.11 fittings.
Applications & Industries
- Thermowell and pressure instrument connections on process lines
- Vent and drain connections on piping and vessels
- Sample connections in refineries and chemical plants
- Small nozzles on storage tanks and skids
- Steam tracing take-offs
- Offshore small-bore connections in duplex and super duplex
Half couplings are one of the most frequently used fittings on new construction and plant modification work, as they allow connections to be added to existing lines with simple welding. See the complete range of forged fittings.
Testing, Inspection, Marking & Packing
Half couplings are produced under our quality assurance process:
- Incoming material verification with PMI testing
- Chemical and mechanical testing to ASTM A105, A350, A182 or the applicable nickel alloy specification
- Heat treatment as required, with pickling and passivation for stainless steels
- Dimensional inspection of length, socket bore and depth, and thread gauging
- Marking with manufacturer’s mark, grade, size, class and heat number
Supplied with EN 10204 3.1 mill test certificates; EN 10204 3.2 certificates and third-party inspection are available on request.
Fittings are packed for export with plastic caps protecting threads and sockets, rust-preventive or VCI wrapping on carbon and alloy steel, and seaworthy wooden cases; marking, tagging and packing to your specification are available on request.
Why Choose Raaj Fittings for Forged Half Couplings?
Raaj Sagar Steels has supplied piping components since 2003 and today manufactures forged fittings at two plants in India for buyers in the Middle East, Europe and the Americas.
- Manufactured in-house — Forged half couplings are made in our own plants, so material, dimensions and delivery stay under our control.
- Ready stock, short lead times — common sizes and grades are held in stock for prompt dispatch; other sizes, grades and specials are manufactured to order.
- Certified quality — ISO 9001:2015, ISO 14001:2015 and ISO 45001:2018 certified; PED 2014/68/EU and IBR supply available, and NACE MR0175 / ISO 15156 material on request.
- 100% material verification — PMI testing on incoming material and EN 10204 3.1 mill test certificates with every order; 3.2 certificates on request.
- Third-party inspection ready — we regularly work with SGS, Bureau Veritas, TÜV and DNV.
- Export documentation — MTCs, certificates of origin, packing lists and inspection reports to suit projects in the GCC, Europe and the Americas.
- Export packing — seaworthy packing with end and face protection, and packing to your specification on request.
- Fast response — our team replies to enquiries within one business day.
Forged Half Couplings — FAQs
A half coupling is a short forged fitting with a socket weld or threaded connection at one end. The other end is welded onto a pipe or vessel to make a small branch outlet.
For small connections such as thermowells, pressure gauges, vents, drains and sample points on larger pipes, headers, tanks and vessels.
It is either set on the outside of the pipe over a hole, or set into the hole, and welded as required by the piping or vessel code.
It depends on the branch and run sizes, wall thicknesses and design pressure. Where reinforcement is required, an MSS SP-97 branch outlet is often used instead.
A full coupling has connections at both ends and joins two pipes in line. A half coupling has a connection at one end only and is used for branches.
Yes. We supply forged half couplings for projects under the European Pressure Equipment Directive (PED 2014/68/EU), and with IBR certification for Indian boiler applications. NACE MR0175 / ISO 15156 compliant material is also available on request for sour service in the Middle East and the Americas.
